Pete C. wrote:

John wrote:

Ed Huntress wrote:
"Stephen wrote in message
...
"Ed Huntress" wrote

"Bob La wrote in message
...
"Ed wrote in message
...

"Pete wrote in message
ster.com...

Karl Townsend wrote:

On Mon, 21 Mar 2011 15:54:38 -0700, Bob La Londe
wrote:

On 3/21/2011 1:56 PM, F. George McDuffee wrote:
On Mon, 21 Mar 2011 11:15:06 -0700, Bob La Londe
wrote:

On 3/21/2011 10:47 AM, Pete C. wrote:

vortex tube cooler

Is it really vortex or just expansion chamber?

Seems if its expansion chamber then I could turn one on the lathe
pretty
darn quick out of aluminum rod stock. Maybe add aluminum cooling
fins
to the first part of the nozzle to assist. Also remember my shop
is in
the Sonoran Desert. Temps in the shop over 100F in the summer
are
common from the end of June into September. Is an air cooler
really
going to get cold enough to make a difference?
===========
Big difference.

A vortex or Ranque-Hilsch tube splits an incoming gas stream
into two output streams, one hot and the other cold. An
expansion chamber simply expands and cools the gas because
of expansion and outputs a single stream.

for more on this see
http://en.wikipedia.org/wiki/Vortex_tube

for some commercial applications see
http://www.exair.com/en-US/Primary%2...rs%20Home.aspx
http://www.stream-tek.com/products/v...FZFoKgodciSg_A
http://www.vortec.com/
and many more

I already saw some of the Stream Tek ones online today. They claim
a
pretty incredible temperature differential. I just might buy one of
theirs if I go that way. The price seems pretty reasonable. Not
sure
about the CFM requirements though. Their medium unit just says
requires
80 PSI. I need to look further and see what their CFM is.

They use A LOT of air and are damn noisy. If you want one, I'm pretty
sure my son still has a unit that he'd let go.

I'm pretty sure his 30k spindle milling aluminum precludes vortex
chiller noise as an issue.

I'm sorry I didn't follow this thread, but how in the heck do you use
liquid coolant with a 30,000 rpm spindle? Unless something has changed
in high-speed machining, that's typically done dry -- even in steel,
where, of course, they use high-performance inserts, many of which
*can't* be run with liquid coolant.

In production machining at those speeds, it's dry, near-dry, or
lean-mist vegetable oil. In aluminum, it is (or was) dry, period.

Well, the one reference to ethanol coolant I made early in this thread
was on a 60,000 to 80,000 rpm machine.

30,000 rpm is not all that hard to achieve nor is it some magic number,
or even expensive if you can stand a certain amount of run out. Heck,
even Harbor Freight rotary tools turn at 15K and they aren't very
expensive at all.

Yeah, I sold Roku-Rokus, with up to 36,000 rpm spindles. And we ran one
in our shop.


A lot of the high speed (commercial) stuff on You Tube uses what looks
like water soluble or water based flood coolants.

Jeez, I'll have to look sometime. Those must be awfully tiny cutters, if
they can use coolant without throwing it off before it gets to the cut.


Who says the coolant is at the actual cutting interface?
It could be pulling all heat from the material ahead and behind the cut.

I suppose so, but why would you pull heat from *ahead* of the cut?

With aluminum and most advanced cutter materials, you don't begin to
approach the surface speeds that would result in unacceptable temperatures,
with any cutter than you can spin at those speeds. And power rarely is a
problem, so reducing cutting forces doesn't mean much compared to machining
steel.

Teeny cutters are typically made from micrograin carbide. When used in
aluminum, they're often diamond-coated, especially for use in modern
automotive castings and other precision castings, which are hypereutectic or
nearly so, and abrasive as hell. Those cutters can take a lot of heat.

I usually skip over the "which coolant for aluminum" threads because, like
this one, they generate a lot of ideas going off in all directions. But, for
the record, the basic idea is that you don't need coolant for most
applications, at least, to keep the tool cool. You will get a small
improvement in tool life using a good lubricant. But, traditionally,
coolants haven't been used. Kerosene was used as a lubricant in the first
half of the last century, mostly to improve surface finish, but sometimes to
deal with edge build-up problems. That became a bigger issue with carbides.

Lubricants, and coolants to some degree, can reduce edge build-up, which can
be a problem in some applications. In milling with carbide tools, however,
the primary use of soluble-oil coolants has been for chip control,
particularly in small-shop and batch-production applications.

But, as always, I'm behind on the thinking in many facets of machining. I
use HSS for almost everything, so edge build-up isn't a big issue for me.
And my hobby projects are machined mostly in 2024 T4, which I get as scraps,
and that alloy does not present much of a build-up problem for me, on my
small lathe. I use a lot of positive rake on aluminum and I make sure the
edges are sharp and the chip-flow area is smooth.


If you really want to cool your tool

http://www.academypublisher.com/ijrt...0105055059.pdf

John

I didn't look at that link, but at IMTS there was at least one demo of
cryo-machining using LN2 for coolant. It looked nifty, but I'll stick to
using my LN2 for making ice cream.


One of the machining magazines I get had a picture of a mill using the
LN2 fed through the center of the tool with a special attachment
something like what you use when you don't have through the spindle
coolant option. I forget which one.

John